ISO means that it is basically a Disc Image. This means that you should be able to use the Disc Copy icon with the green arrow. Then either use the Image File tab, or the Disc Copy, to add and then burn.
Another way to burn it would be to open the ISO, disc image, to the desktop exposing the Video and Audi TS folders. Then in Toast, click on the Movie Section tab, and then the Video TS folders tab, and add the TS folders to the window and burn.
Hope that helps.